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Method of Sampling and Collecting Particulate Contaminants in Drives by Using a High Flow Through Sampling/ Collecting/ Counting System

IP.com Disclosure Number: IPCOM000122521D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Bergin, M: AUTHOR [+3]

Abstract

The low air sampling rate used in small drives and the small/restricted outlet to the particle counter limit the ability to determine the true particle contamination levels in drives. By using a high air- flow through the drive and a much less restricted exit to the counter, sampling of drive air and particle collecting/counting efficiency can be considerably improved.

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This is the abbreviated version, containing approximately 52% of the total text.

Method of Sampling and Collecting Particulate Contaminants in Drives
by Using a High Flow Through Sampling/ Collecting/ Counting System

      The low air sampling rate used in small drives and the
small/restricted outlet to the particle counter limit the ability to
determine the true particle contamination levels in drives.  By using
a high air- flow through the drive and a much less restricted exit to
the counter, sampling of drive air and particle collecting/counting
efficiency can be considerably improved.

      Fig. 1 illustrates a typical air sampling and particle counting
set-up used for small drives.  The present invention involves the use
of a high air flow through the drive (up to 9.5 cfm), and a
significantly less-restricted flow to the particle counter.

      To reduce the restriction to air flow and prevent a high
pressure build-up in the drive, one end of the drive is opened.  This
is achieved by removing the side or top cover of the drive.  The
drive is then fitted and sealed vertically into a collection chamber
which is a rectangular box with a shaped air path, as illustrated in
Fig. 2.

      Compressed air is passed through a 0.2-micron filter and
introduced into the drive from the opposite side of the large exit,
through a 0.125-inch vertical inlet.  Since compressed air is used, a
positive pressure is built up in the drive.  The positive pressure
prevents external air from leaking into the drive.  The air entering
the drive will get mixed into the drive and exit through the
collection chamber to the particle counter, carrying with it a large
fraction of particles present and being generated in the drive.

      The air f...